Changeover device



Feb. 5, 1935. c. 1.. LOOTENS 1,990,388

CHANGEOVER DEVICE Filed March 4, 1930 Inventor: chaYles L.L,ootens,

E HLs Attorne g.

Patented Feb. 5, 1935 UNITED STATES PATENT OFFICE CHANGEOVER DEVICE NewYork Application March 4, 1930, Serial No. 433,165

1 Claim.

My invention relates to electrical apparatus including a plurality ofsignal producing devices and a signal responsive device which device isadapted selectively to be put into operative connection with any one ofthe signal producing devices. More particularly my invention relates toapparatus for making a sound record or for reproducing sound from asound record electrically from any one of a plurality of devices whichproduce current impulses that vary in accordance with the sound waves.

In the case of apparatus for reproducing sound from film or disk recordsby electrical means it is often desirable to continue the soundreproduction without interruption from one film or disk to another. Forthispurpose two or more separatepick-up devices usually are employed sothat when the end of one film or disk record is reached the connectionto the sound producer may be transferred quickly to the pick-upcooperating with the next film or disk record. It is found that whensuch a transfer of the circuit connections is made by the use of anordinary double pole switch very objectionable noises are produced bythe sound producer at the instant of transfer. Also during reproductionfrom one record, noises and objectionable sounds foreign to the record,such as cross talk, often are heard which are traceable to one of thesound pick-up devices which is not at that time operatively connectedthrough the switch to the sound producer. It is the object of myinvention to provide improved apparatus of the above-mentioned characterwhereby the transfer from one signal 35 source to another may be madewith the resulting production of a minimum disturbance and in whichduring the use of one signal source objectionable signals may beprevented from coming from another signal source not at that timeconnected for service.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing, and its scope will bepointed out in the appended claim.

The single figure of the drawing illustrates diagrammatically anembodiment of my invention wherein sound is adapted to be produced fromeither one of two devices for converting film sound records intoelectric vibrations. The two devices which I have illustrated in aconventional manner as the two combined film sound-picture projectors 1and 2 each include in addition to picture projecting means a suitableand well known pick-up means for converting a photographic sound recordon the picture film shown a sound producer, for example, a loud 1speaker of suitable and well known construction, and connected to thesound producer I have represented at 4 a suitable and well knownamplifier which, for example, may be of the thermionic type. While Ihave made reference to but one amplifier 4, other amplifiers,transformers, etc., often are employed and arranged in close associationwith the pick-up devices, but for the sake of greater clearness in thedrawing, the showing of such details has been purposely omitted as theyform no part of my present invention.

Between the amplifier 4 and the projectors 1 and 2 is the switchingdevice 5 now to be described by means of which the sound producer 3 isoperatively connected with either one of the projectors 1 and 2. Theswitching device 5 has the supporting base or frame 6 upon which aremounted the various elements of the switch, the signal apparatus and theterminal connectors or binding posts 7, 8 and 9. To the latter areconnected pairs of leads 10, 11 and 12 respectively from the projectors1 and 2 and from the amplifier 4. Prior to my invention an ordinary twopole double throw switch had been used to connect the leads 12 witheither leads 10 or 11. When such a switch is operated to transfer thereceived sound current, commonly termed the signal, from one projectorto the other both sides of the circuit necessarily are opened andclosed. This, by reason of the great amplification produced by theamplifier 4, results in an objectionable and loud noise from the soundproducer. Disturbing noises are also often given out by the soundproducer during the operation of one projector as a result of the workof the operator jector which at that time is not in service and the uamplifier, it is probable that the objectionable results mentioned aboveare due to a large extent, if not entirely, to electrostatic or capacityeffects at the switch terminals.

According to the construction and arrangement which I have devised, theleads 10, 11 and 12 are connected in a series circuit and a switch isprovided which enables the operator at will to short circuit either.leads 10 or 11 according towhichever projector is at the time out ofservice. Short circuiting the leads from a projector equalizes any andall potential diiferences that may exist between the leads due to noiseor sound impulses coming from that projector. Referring again to thedrawing, conductors 14., 15 and 16 serve to connect in a series circuitthe binding posts 7, 8 and 9 of the switch. The structure of the switch,which in reality is a relay, comprises the core 17 having thereon thewinding 18 and having the enlargement 19 at one end and the pole piece20 at the other. The resilient switch blade 21 of magnetic material isrigidly secured at one end to the portion 19 and at the other end hascontacts which are arranged to engage the fixed contacts 22 connectingwith the conductors l and 16. Blade 21 is connected to conductor 14.When the winding is deenergized the switch short circuits the leads fromprojector 2 and when energized short circuits the leads from projector1.

For the convenience of the operator, I have operate with the fixedcontacts 27 in the lamp control circuit. The switch winding and pilotlamps are connected to be energized by the battery 28 for controllingthe winding; I have shown thetwo hand operated switches 29 and 30 eitherment which I have shownand described the transfer of the signal from oneprojector to the other is accomplished simply by removing the shortcircuit of the leads to one projector and applying a short circuit tothe leads of the other projector. A minimum circuit disturbance isthereby set up in making the transfer and no disturbing noises or crosstalk eifects are heard during the operation of one projector which havetheir origin in the other projector.

Although I have illustrated my invention as including but two projectorsit is not limited to two but is applicable to a system including anynumber of projectors, it being understood that the switch in any casewill be constructed to open the short circuit only of the leads whichconnect with the particular projector to be used. As indicated above, myinvention is applicable to recording apparatus in which the circuitconnections to the film or disk recorder may be transferred from onesound pick-up to another.

I have chosen the particular embodiment described above as illustrativeof my invention andit will be apparent that various modifications may bemade without departing from the spirit and scope of'my invention whichmodifications: I aim to cover by the appended claim. I

What I claim as new and desire to secureby Letters Patent of the UnitedStates, is:-

Apparatus for operatively connecting a sound reproducer with one or theother of two separate sound pick-up devices, comprising a base memberhaving pairs of circuit terminals adapted for connection with therespectivepick-up devices and sound reproducer, conductive meansconnecting" said pairs of terminals in series, and a switch .gn saidbase member comprising a single movable contact member and cooperatingfront and rear contacts, said member and contacts having con-- nectionswith said conductive means and arranged;

in one position of the member to apply ashort circuit to one pair ofpick-up. terminals and in the other position to apply a short. circuitto theother pair of pick-up terminals.

CHARLES L. LOOTENS.

